The present invention relates to the art of automotive lift systems and, more particularly, to lifts of the type used in automobile service stations.
The invention more particularly relates to the area of in-ground non-hydraulic automotive lift systems.
At about the time of the advent of in-ground hydraulic automotive lift systems, which occurred in the year 1921, certain limited efforts were made to create a non-hydraulic automotive lift employing a thrust screw in combination with a load nut mounted thereon. Examples known to the inventor of these efforts are reflected in U.S. Pat. Nos. 1,585,596 (1926) to Menges and 1,650,438 (1927) to Gass. Notwithstanding such early experimentation at about the time of the initial development of the in-ground hydraulic lift, most later efforts in connection with automotive screw lifts related to above ground systems of the type reflected in U.S. Pat. No. 3,602,338 (1971) to Sherry. However, For the most part, the use of screw lift systems in the automotive area have been limited to jack-type devices for use above ground and with relatively light vehicles, as is reflected in U.S. Pat. No. 3,532,322 (1970) to Webster. Therefore most in-ground lifts during the period 1921 to 1970 were hydraulic, not screw lifts.
It is noted that, in non-automotive areas, such as the elevator lift art, various screw drive mechanisms have been proposed, as, for example, is shown in U.S. Pat. No. 3,468,401 (1969) to Letz.
By about 1970, government and the public became aware that in-ground hydraulic lifts, utilizing as they do hundreds of gallons of hydraulic fluid per year, give rise to an environmental hazard of proportions which are only now becoming fully apparent. More particularly, hydraulic fluid, while for the most part comprising an oil-based hydrocarbon, includes certain caustic and heavy metal additives including iron, lead, copper, tin, aluminum, nickel, phosphorus, molybdenum and cadmium. These additives, if permitted to penetrate the water table, can give rise to contamination of the water supply at concentrations of only a few parts per billion. There is, thereby, a burgeoning awareness on the part of environmental officials and others that the hydraulic lift, which has been a standard in service stations throughout the world since 1920, presents an actual and/or potential health hazard of still unmeasured magnitude, whether the lift is positioned in-ground or above ground, as has been common since 1970.
The above problem, as may be appreciated, is more acute in areas where the water table is very high, such as in coastal areas of Florida and Louisiana where the water table can be as high as two feet below the surface. Thereby, the typical prior art in-ground hydraulic lift, which is installed to a depth of about nine feet in the ground, presents a particularly serious hazard in such areas. Further, the state-of-the-art of monitoring (typically means such as microwave and electronic systems) of the extent, location and form of ground pollution has made it feasible to conduct environmental surveys of virtually any business or industrial site for purposes of location of pollution, whether occurring as a result of system leakage or otherwise. It is anticipated that government will soon begin to use this capability.
In response to the above factors, so-called above-ground lifts were developed. However, a difficulty with such above-ground lifts is that they are not space efficient, that is, four in-ground lifts can fit into the space of three above-ground lifts. Accordingly, above-ground hydraulic lifts have several major problems, that is, they are not space-efficient and create floor space clutter. The best solution therefore would be that of an in-ground, non-hydraulic system that could compete with above-ground hydraulic systems. Such a solution is offered by the present invention.
The instant invention may, thereby, be viewed as a response to the recognition of the environmental hazards associated with all hydraulic lift technology.